@Manuel_Soberanis
You cannot really do this with a single select option, in fact there is little you can do with that field type.
Even with a formula field it is not straightforward as a blank cell and 0 report as the same thing. Look at Differentiating between blank and zero
Taking that into account a formula would still result in the best option for you. A nested IF() would likely perform the best:
IF(COUNTA({Amount Used}) = 0, “Pending”,
IF({Amount Used} > 0, “Used”,
IF({Amount Used} = 0 ,“Void”, “”)))
The first line of this formula looks to see if the cell is indeed blank or is just recorded as a zero value. If it is indeed blank if brings back the word “Pending”
The second and third lines above utilize basic comparisons to bring out the other two states you are seeking.
While this will not provide you with a sleek single select type button field, it would appear that you are not looking for that field type. You do not want to alter this cell individually but would rather have the airtable do the work for you. If you are looking to jazz up the look of the returned language I would suggest adding emjoi characters or something, see the listing on conditional formulas with emojis Or if you are on the paid plan you can use conditional formatting to alter color on the entire record.
Hope this helps
